Okay, recently my father and I purchased a 1955 Pontiac Chieftan. Its a great looking car. This is our first classic car but its never to early to start right? Course the floor boards need replacing and there are some dents but all and all its nice. The engine runs but we definately want to replace it. Problem is we know next to nothing about engines. We want to put a v-8 in it to keep with the spirit of 55 being the first year that GM put v-8s in, but we don't know what size or how to get better mileage. This is primarily my fathers car. He will use it on a day to day basis basically, so he would want the car to have good mileage. He's not that into performance so what would be the best way to go? What size and what trans should we get? Also, what are different strategies to getting better gas mileage with a V-8, what parts? We would be looking at getting a crate motor rather then rebuilding another engine. Also if you recommend a specific engine and know a website that sells them let me know the site and the price.

Thanks in advance.